3-Halomethyl-{66 {hu 3-Cephalosporin esters

ABSTRACT

3-Halomethyl- Delta 3-cephalosporin (sulfide) esters and sulfoxides thereof, prepared by reacting a phosphorus halide with a 3-hydroxymethyl- Delta 3-cephalosporin sulfoxide ester, which sulfide esters can be de-esterified to form antibiotics, and which sulfide ester and sulfoxide ester products are useful as intermediates in the production of known and new antibiotics.

United States Patent Murphy et a1.

1 1 Nov. 25, 1975 3-HALOMETHYL-A -CEPHALOSPORIN ESTERS inventors:Charles F. Murphy; J. Alan Webber, both of Indianapolis, Ind.

Eli Lilly and Company, lndianapolis, 1nd.

Filed: Aug. 10, 1970 Appl. No.: 62,699

Related US. Application Data Continuation-impart of Ser. No. 883,231,Dec. 8, 1969, abandoned, which is a continuation-in-part of Ser. No.811,640, March 28, 1969, abandoned Assignee:

US. Cl 260/243 C; 260/239.1; 424/246 Int. Cl. C07D 501/20- Field ofSearch 260/243 C References Cited UNITED STATES PATENTS Webber 260/243 C3,647,786 3/1972 Cooper 260/243 C 3,658,799 4/1972 Eardley et a1 260/243C 3,716,533 2/1973 Humber 260/243 C Primary ExaminerNicholas S. RizzoAttorney, Agent, or FirmWi1liam C. Martens, Jr.; Everet F. Smith 6Claims, N0 Drawings 3-HALOMETHYL-A CEPHALOSPORIN ESTERS CROSS-REFERENCEBACKGROUND OF THE INVENTION Cephalosporin C, obtained by fermentation,has been defined as having the following structure R-CO-NH- H- H2 i-CH2O wa OOH where R is HOOCCl-I(Nl-I )(CH It is also known as7-(5-aminoadipamido)cephalosporanic acid. It has weak antibioticactivity, but it is important as a source of the cephalosporin Cnucleus, i.e., 7- aminocephalosporanic acid (7-ACA) OOH groups and/or byreplacing the acetoxy group attached to the 3-methyl carbon atom withappropriate nucleo- '55 philic groups now well documented in theliterature.

In continued research desacetoxycephalosporin compounds, i.e., compoundsof the structure where R is the residue of the acyl group having beenprepared. An important known antibiotically active compound in thisclass is cephalexin, an orally active cephalosporin antibiotic. Morinand Jackson (U.S. Pat. No. 3,275,626) discovered a process for preparingthe desacetoxycephalosporanic acid derivatives by rearranging apenicillin sulfoxide ester to the corresponding desacetoxycephalosporinester, and then removing the ester group. Desacetoxycephalosporanic acidderivative antibiotics are thus obtainable from a penicillin startingmaterial. These compounds are sometimes, for convenience, referred to asbeing derivatives of 7- aminodesacetoxycephalosporanic acid (7-ADCA)having the structure I coon cO-H 4H and which is sometimes written inthe zwitterionic (inner salt) form.

One of the unique advantages of A -desacetoxycephalosporin compounds,that is, compounds of the general formula 0 u R-c-un-?a-cl:ne acn co-nsact-CH a coonwherein R is the residue of the acylamido group in the7-position and R is hydrogen, a salt forming cation, an ester group oran anionic charge when the CO0- forms a salt with a cation either withinor outside of the molecule, is that such compounds can now be preparedfrom penicillin sulfoxide esters by the Morin-Jackson process.

In efforts to improve and expand the properties of these penicillinderived semi-synthetic cephalosporin substances, efforts have beenexpended on changing the 3-methyl group of the above A-desacetoxycephalosporins to a group which gives the resultingcaphalosporin compound enhanced antibiotic activity against one or moreGram-positive or Gram-negative microorganisms. However, to date atleast, it has not been possible to convert directly a A-desacetoxycephalosporin to a 3-( substituted-methyl)-A-cephalosporin inany significant yield. A suggestion in Belgian Pat. No. 684,288 that the3-methyl group of a A -desacetoxycephalosporanic acid ester could bebrominated with N-bromosuccinimide (NBS) to give the corresponding3-bromomethyl-A -cephalosporin ester has not been accomplished to ourknowledge. Webber and Van Heyningen (U.S. patent application Ser. No.703,523, filed Feb. 7, 1968) now abandoned but replaced byapplicaalosporin. That process involves isomerizirig the A 1 double bondto the A position, treating the resulting A -desacetoxycephalosporincompound witha brominatingagent such as N-bromosuccinimide (NBS) to formthe corresponding A -3-bromomethyl compound, and,if desired, replacingthe bromine with an appropriate nucleophilic group. Thereafter, the3-(nucleophilemethyl) -A -cephalosporin compound can be isomerized tothe A position by oxidizing the sulfur atom thereof with an inorganicperacid having a reduction potential of at least +1.5 volts andcontaining only nonmetallic elements, organic carboxylic peracids, orwith a mixture of hydrogen peroxide or an acid having a dissociationconstant of at least as described in more detail in 'Cooper U.S.application Ser. No. 764,939, filed Oct. 3, 1968, now U.S. Pat. No.3,647,786, issued Mar. 7, 1972 during which reaction the double bond ismoved to the 3-position and then the resulting 3-(nucleophile-methyl)-A-cephalosporin sulfoxide compound can be reduced as describedby Murphyet al. in U.S. application Ser. No. 764,925 filed Oct. 3, 1968 now U.S.Pat. No. 3,641,014, to the sulfide state. Any protecting groups, e.g.,ester groups, are removed by known methods to obtain the desired3-(nucleophile.

methyl)-A -cephalosporanic acid derivatives. The bromine in the3-bromomethyl-A -cephalosporanate esters of Webber and Van Heyningen maybe replaced with any oxygen, carbon sulfur, or nitrogen containingnucleophilic group. Subsequent oxidation and reduction reactions causeno problems when the resulting 3-(nucleophile-rnethyl)-A -cephalosporinester is one having an oxygen or carbon bonded'to the 3-methyl carbonatom. However, when the nticleophile is one having a nitrogen or sulfurbonded to the B-methyl carbon atom, side reactions sometimes occur inthe nucleophile group during the oxidation step in attempts to convertthe sulfur in the 1-position to the sulfoxide state, thus lowering theyield of. the desired Zi-(nucleophilemethyD-N-cephalosporinester-l-oxide. There is a need in the cephalosporin chemical art for aprocess for preparing 3-halomethyl-A scephalosporin esters so that thehalogen can be replaced with an, appropriate nucleophilic group in theprocess for making any desired known or new A -cephalosporin antibiotic.I

It is an object of this invention to provide an alternative process forpreparing 3-halomethyl-A -cephalosporin esters which are especiallyuseful as intermediates in production of new and known nitrogen andsulfur containing 3-(nucleophile-methyl)-A -cephalosporin antibiotics.

It is a further object of this invention to provide a process forpreparing 3-halomethyl A -cephalosporins which have antibiotic activityand which can be used to.

form 3-(nucleophile-methyl)-A -cephalosporins, which do not need to besubjected to oxidation and reduction conditions.

It is another object of this invention to provide a process whichcircumvents or avoids the problemsthat can result in some casesfollowing the conversion of a 3- bromomethyl-A -cephalosporin ester to a3-( nucleophile-methyl)-A -cephalosporin ester wherethe nu-.

cleophile has an oxidizable nitrogen or sulfur "atom I therein.

Other objects, advantages, and aspects of this iriven tion will becomeapparent to those skilled in the art from the description which follows.

SUMMARY Briefly, we have discovered that 3-halomethyl-A cephalosporinesters can be prepared by reacting a ganic liquid diluent at atemperature of from just above I the freezing point of the reactionmixture to about i I, 50C. When a phosphorus trihalide is used atmoderate temperatures, the product is a 3 -halomethyl-A -ceph- Ialosporin ester in which the sulfur in the 1-position isin 1 the sulfideor bivalent state. This means that no sepa rate reduction step is neededwhen phosphorus trichlo- I, ride or phosphorus tribromide is used. Whentemperatures below about 25C are used with equimolar ratios ofphosphorus trihalide, the 3-bromomethyl-A cephem sulfoxide product canbe obtained.,When a phosphorus pentahalide or a phosphorusoxyhalide isused, the product of the resulting reaction is a 3 halomethyl-A-cephalosporin sulfoxide ester, which, can be used as such as anintermediate for replacingthe halogen with an appropriate nucleophilicgroup. These products are especially useful as intermediates for halogendisplacement by basic nucleophiles, which, basic pH condition mightotherwise cause the, A -double, 7

bond to isomerize, to the A -position. The sulfoxide pro:

tects or keeps the A double bond in the 3-position.

This invention also includes a process for converting the 3-chloromethyland 3-br0rnomethyl-A -cephalosporin ester products to the correspondingnew. 3-'

iodomethyl-A -cephalosporin compounds by reacting the 3-chloromethylor3-bromomethyl-A -cephalospm rin ester productof the first step with analkali metal iodide in an appropriate anhydrous organic liquid solventsystem.

I DETAlLED DESCRIPTION OF THE INVENTlON The phosphorus halide used inthe first step of the phorus pentachloride, phosphorus ybromide (O=PBrWhen phosphorus pentabromide.

.is used, temperatures in the lower part of the range must be used.Phosphorus halide compounds having i organic radicals satisfying one ortwo valencesof phosphorus, with at least one remaining phosphorusvalence. being satisfied by chlorine or bromine can be used. Suchcompounds should have a molecular, weight below about 500. Examples ofsuch compounds which i I could be used include methylphosphonousdichloride, dimethoxyphosphi- I nous chloride, diphenoxyphosphinousbromide, and

phenylphosphonous dibromide,

the like. Those skilled in the art can readily determine the other typesof phosphorus halides from these exam ples.

When the pounds are being prepared, an iodide ion source is mixed withthe 3-chloromethylor 3-bromomethyl-A s 3-iodomethyl-A -cephalosporincomcephalosporin ester in an organic solvent. The iodide ion ispreferably added as an alkali metal iodide salt, e.g., the sodium,potassium, lithium, rubidium or cesium salt, but as a practical,economic matter, only the sodium and potassium salts are of interest.Alkaline earth metals including magnesium, iodide salts/and otherreactive metal iodide salts can also be used but are not preferred.

The 3-hydroxymcthyl-A -cephalosporin sulfoxide ester starting materialcan be prepared by treating a corresponding 3-halomethyl-A-cephalosporin ester with a mixture of an organic solvent and water inan organic aprotic diluent such as benzene to form the 3-hydroxymethyl-A -cephalosporin ester, and then oxidizing the 3hydroxymethyl-A cephalosporin sulfoxide by known methods which resultsin the formation of the desired 3-hydroxymethyl-A -cephalosporinsulfoxide ester. The organic solvent can be dimethylsulfoxide,diethylsulfoxide, or the like. The dialkylsulfoxide/water mixture shouldcontain at least about 25 percent by volume of the dialkylsulfoxide.However, the water content of the mixture should be at least equivalentto.

the halide content of the 3-halomethyl-A -cephalosporin ester. Forexample, p-rnethoxybenzyl 3-hydroxymethyl-7-phenoxyacetamido-A-cephem-4-carboxylate-l-oxide can be prepared by reactingp-rnethoxybenzyl 3-bromomethyl-7-phenoxyacetarnido-A-cephem-4-carboxylate with 10 molar equivalents of water (relative tothe 3-bromomethyl compound) in a 1:1 v/v mixture of benzene anddimethyl-sulfoxide followed by treatment with 85 percentm-chloroperbenzoic acid in a mixture of isopropyl alcohol and methylenechloride. The 2,2,2-trichloroethyl 3-hydroxymethyl-A -cephem-4-carboxylate esters can be prepared by oxidizing with a peracid such asrn-chloroperbenzoic acid the 2,2,2- trichloroethyl 3-hydroxymethyl-A-cephem-4-carboxylate compounds disclosed, e.g., in South African Pat.No. 66/5105 (Derwent No. 26121, issued Apr. 25, 1967) in an organicsolvent system such as methylene chloride /20% v/v isopropanol.

The phosphorus halide and the 3-hydroxymethyl-A cephalosporin sulfoxideester reactants are combined in a substantially anhydrous aprotic liquidorganic solvent such as benzene, toluene, xylene, heptane, hexane,methylene dichloride, chloroform, carbon tetrachloride, dioxane,tetrahydrofuran, lower alkyl alkanoates such as ethyl acetate, amylacetate, lower alkanonitriles such as acetonitrile, proprionitrile,nitroalkanes such as nitromethane, nitropropane. A tertiary aminepreferably is added to moderate the effect of hydrogen halide and toneutralize the by-product hydrogen halide. When temperatures below about25C are used, substantially any tertiary amine can be used. However,when only moderately low temperatures are used (25C to +C), the selectedtertiary amine preferably has a pKa with the range of about 4.5 to about5.8. Examples of preferred tertiary amines are N,N-dimethylaniline,pyridine, quinoline, and the like. The mixture is preferably maintainedat relatively low temperatures, e.g., 75C to +50C to control the speedof the reaction which ensues spontaneously in most cases. The3-halomethyl-A -cephalosporin esters are formed from at least anequimolar amount of phosphorus trihalide when reaction temperaturesabove about 25C are used. The 3-l1alomethyl-A -cephalosporin sulfoxideesters are formed from an approximately equimolar amount of a trivalentphosphorus trihalide when temperatures below about '25C- are used.

The 3-halomethyl-A -cephalosporin sulfoxide esters are formed from thephosphorus pentahalide or phosphorus oxyhalide reactants. Some warmingup to 50C may be required when the organic phosphoric halides are used.Stoichiometric equivalents of the reactants may be used, particularlywhen sulfoxide products are desired, but it is preferred to use at leasta slight excess of the phosphorus halide relative to the3-hydroxymethyl-A -cephalosporin sulfoxide ester to insure completereaction thereof. From 1 to 10 moles of the phosphorus halide may beused per mole of the sulfoxide ester reactant, particularly whentrivalent phosporus trihalides are used to form the reducedcephalosporin ester products. Generally from 30 percent to percentexcess of phosphorus halide will be sufficient to insure substantiallycomplete reaction.

When the reaction is completed, the 3-halomethyl- A -cephalosporin esterproduct may be separated from the reaction mixture by conventionalmethods. For example, the mixture may be washed with aqueous sodiumchloride, sodium bicarbonate, hydrochloric acid solutions and then withwater to separate soluble impurities. The organic layer containing theproduct may then be separated and evaporated to substantial dryness togive the substantially pure 3-halon1ethyl-A cephalosporin ester product.

New compounds, obtained according to the process of this invention, havea formula wherein R is an amino-protecting group, and R is acarboxyl-protecting ester group, and X is chlorine, bromine, or iodine.

The amino-protecting group represented by R in the above can be anygroup known to protect the nitrogen to which it is bonded from attach bythe phosphorus compounds. Examples of amino-protecting groups which canbe used include trimethylsilyl, triphenylmethyl, butoxycarbonyl, or asis most practical and preferred, an acyl group. Many acyl groupssuitable for use in the R position are already known in the penicillinand cephalosporin antibiotic literature. When it is desired to start theoverall process from a penicillin, the preferred acyl groups for use inthe R position can be generally described by the formula where Ardenotes 2-thienyl, or

wherein m is an integer of from O to 4, n is an integer of from 1 to 4,Z is oxygen or sulfur, or a chemical bond, R' and R"" are, separately,hydrogen or methyl, or R" is hydrogen when R can be an N- protectedamino group such as N-(tert-butoxycarbonyl)amino,N-(benzyloxycarbonyl)amino, N-(allyloxycarbonyl)-amino,N-(cyclopentyloxycarbonyl- )amino,N-(Z-methoxycarbonyl-l-methylvinyl)amino (the enamine frommethylacetoacetate), or the like and n is l; and Y is hydrogen orasubstituent on the phenyl ring carbon atoms such as fluorine, chlorine,bromine, iodine, C, to C -alkyl, C, to C -alkyloxy, N-protected-alpha-amino-C, to C -alkyl, butoxycarbonyl, nitro, cyano,trifluoromethyl or the like, and w is an integer of from 1 to 2 and ispreferably 1. Specific examples of some such acyl groups includephenylacetyl phenoxyacetyl phenylmercaptoacetyl benzyloxyacetylbenzylmercaptopropionyl phenylpropionyl phenylethylmercaptopropionylphenylbutoxybutyryl 3-fluorophenoxyacetyl 4-bromophenylacetyl2-chlorobenbyloxypropionyl 3-methylphenylbutyryl 4-propylbenzylmercaptoacetyl 4-nitrophenylmercaptoacetyl 4-aminomethylphenylacetyl3-cyanophenylpropionyl 4-trifluor0phenoxyacetyl Z-thienylacetyl,

2[N-(tert-butoxycarbonyl)amino]-2-phenylacety1) or the like.

Numerous other compounds which form aminoprotecting acyl groups whichcan be used in the R position are known in the prior art; e.g., thosedisclosed in the Behrens et al. US. Pat. Nos. 2,479,295 to 2,479,297 and2,562,407 to 2,562,411 and 2,623,876.

If 7-aminocephalosporanic acid (7-ACA) is to be used as the startingmaterial, the preferred 7-aminoprotecting group will be one which is notonly easy to put on the 7-amino nitrogen, but one which can be removedeasily after the desired series of reactions on the 3-position methylgroup are completed. In such event, the preferred 7-amino-protectinggroup can be a simple C, to (l -alkanoyl group such as formyl, acetyl,propionyl, butanoyl, hexanoyl, a C to C -chloroalkanoy1, particularlythe a-chloroalkanoyl groups, such as 2- chloroacetyl which groups areput on by reacting 7-ACA with the respective acid chloride. If theselected overall process route to the cephalosporin antibiotic calls foracylating 7-ACA, an ester of 7-ACA, 7-ACA sulfoxide or a 7-ACA sulfoxideester with the final acyl group; one can acylate with, for example, anactivated form of N-protected phenylglycine. Such activated form mightbe the mixed anhydride formed by reacting isobuty] chloroformate and2-[N-(tert-butoxycarbonyl)amino]-2-phenylacetic acid.

The R symbol in the above structural formula repre-.

sents an ester group, preferably one that is easily removable by the useof trifluoroacetic or formic. acids or a non-oxidizing mineral acid suchas a hydrochloric acid, sulfuric acid, or by the use of zinc in analkanoic acid such as formic acid, acetic acid, trifluoroacetictertpentyl, l, l -dimethyl-2-propenyl,

butynyl, and l,l-dimethyl-2-pentynyl, benzyl, methoxybenzyl,nitrobenzyl, phenacyl, trimethylsilyl, benzhydryl, phthalimidomethyl,and 'succinimidomethyl.

The 3-halomethyl-A -cephalosporin ester products i are useful asintermediates in the direct preparation of antibiotic cephalosporincompounds by removing the ester group therefrom by a variety of knownmethods. The 3-halomethyl-A acephalosporin sulfoxide ester.

products may be reduced to cephalosporinester com-.

pounds and then de-esterified by known methods to prepare the free3-halomethyl-A -cephalosporin acid 1 derivatives which areantibiotically active. Alternatively, in some cases, the sulfoxideestercanbe deesterified first and then reduced.

Examples of reduction methods which may beusedi include the treatment of(a) the 3-ha1omethyl-A -ceph g g alosporin sulfoxide acid or ester with(b) areducing agent selected from the group consisting of:

1. hydrogen in the presence of a hydrogenation catal lyst 2.. stannous,ferrous, cuprous, or manganeouscations" I 3. Dithionite, iodide, orferrocyanide anions I 4. Trivalent phosphorus compounds having amolecular weight below about 500 5. halosilane compounds of the formulawherein X is chlorine, bromine, or iodine, and each of Rand R ishydrogen, chlorine, bromine, iodine, era 7 x hydrocarbon radical freefrom aliphatic unsaturation and having froml to 8 carbon atoms, and

6. a halomethylene iminium halide of the formula I i i where X ischlorine or bromine, and wherein each of R and R, taken separately,denotes a C, to C -alkyl or, taken together with the nitrogen towhichthey are I bonded, complete a monocyclic, heterocylic ring having from 5to 6 ring-forming atoms and a total offrom 4 to 8 carbon atoms, and anactivating agent whichis (c) an acyl halide of an acid of carbon,sulfur, or phosphorus, which acid halide is inert to reduction by thereducing agent, and which acid halide has a second order hyi drolysisconstant equal to or greater than that of benzoyl chloride, or (d) acyclic sultone of the fo'rmula 8 I y acid, or a mixture containing suchacids, or by hydrogenation in the presence of a suitable hydrogenationcata- 1,1-dimethyl-2- 7 I i thiophene-Z-acetic acid, acid chloride, ormixed anhy- 0 CHR purpose, these compounds can be administered, e.g.,orally in doses of from about 250 mg. to about 500 mg., o1=s\ inpulvules or tablets, 4 to 6 times a day to patients of CHR [CH4]" about70 kg. body weight.

Specific cephalosporin starting materials, intermediwhere n is Oor l,and each R is defined separately as ates and products of the process ofthis invention are hydrogen or C, to C -alkyl with not more than onesuch named, for convenience, by use of the cephem no- R being C to C-alkyl, in a substantially anhydrous liqmenclature system. Penam"nomenclature for the uid medium at a temperature of from about 20 C. topenicillins is described by Sheehan, Henery-Logan, and about 100 C. toform the 3-halomethyl-A -cephalospo- 10 Johnson in the Journal of theAmerican Chemical Socirin acid or ester. ety (JACS), 75, 3292, footnote2, (1953), and has been The compounds of both formulas l and ll areprimaradapted to the cepheiospol'ins y Morin, Jackson ily of interest inthe preparation of known and new anti- Flynn. a ROeSkB. l- 3400, inbiotically active cephalosporin compounds, which is cordance with thesesystems of nomenclature, pheaccomplished by replacing the chlorine,bromine, or nam and cepham refer respectively to the following iodineatom on the 3-halomethyl carbon atom with the saturated ring systems:

desired nucleophilic group. For example, p-nitrobenzyl Cephem refers tothe cepham ring structure contain- 3-chloromethyl-7-phenoxyacetamido-A-cephem-4- ing a double bond, the position of which is indicated bycarboxylate can be treated with sodium or potassium a efixed A with asuperscript number denoting the acetate in an organic medium to form l ylowest numbered carbon atom to which the doubleacetoxymethyi'7'PhenoxyacetamidoAa-cephem4-631- bond is connected, or bythe word delta" with the boxylate, and then the ester group can beremoved by hydrogenation by known methods to obtain a knowncephalosporin antibiotic, 3-acetoxymethyl-7-phenoxyacetamido-A-cephem-4-carboxylic acid. If more active antibiotics are desired, the7-acylamido group can be cleaved by known methods, e.g., as described in40 US. Pat. No. 3,188,311, issued June 8, 1965, and then the resultingcephem nucleus can be acylated with 2'- same number relationship.Sometimes, the number is used before cephem without the symbol A or theword delta to indicate the same double bond position. Thus, penicillinV, 6-phenoxymethylpenicillin, can be named6-(phenoxyacetamido)-2,2-dimethyl-penam-3-carboxylic acid, and7-phenoxyacetamido-cephalosporanic acid can be named as3-acetoxymethyl-7-phenoxyacetamido-A -cephem-4-carboxylic acid. Anexample dride to form the corresponding of a 3-halornethyl-A-cephalosporin ester of this inventhienylacetamido)-A -cephalosporinester which can 5 by this nomenclature System can be namtfd Z then bede-esterified to the acid antibiotic, or treated but)"3'chlowmethyl'7'phevoxymethylacetamldo'A with a nucleophilic reagent todisplace the chlorine or cephem'4carboxylate from tert'bmyl bromine andthen be de-esterified to form the moreachydroxymethylJPhenoxyacetam'do'Aif'cepllem'4' tive antibiotic. By thisprocedure, cephalothin, a known carboxylate'lcxide and Phosphorusmchlondeantibiotic, available commercially as the sodium cephawe havealso found that 3-hyd oxymethyl A -ceph- 10min can be Obtained from theProducts and y alosporin esters will also react with phosphorustrihalithe Process of this invention Also the 3-haiomethyidos such asphosphorus tribromide or trichloride to A -cephalosporin ester productof this invention can be f the col-respbnding 3 bl-0momethy] or 3.

treated with a sulfur-containing nucleophile such as ch10mmethyl Azcepha|osporin derivative For exammethyl meriaptan to f the 55 ple,tert-butyl 7-phenoxyacetamido-3-hydroxymethylcephalosporm ester. This3-methylthlomethyl-A -ceph- Az cephem 4 carboxylate can be reacted withphos alosporin ester can be treated as described above to rephorustribromide to form tembutyl 7 phenox move the f? gioup or 9amino'pmtectmg group yacetamido-3-bromomethyl-A -cephem-4-carboxylate.and replacmg wlth a .ieslred acyl group i as an However, that process isof no particular value to the g fij g g by ggl f s z i gr sg processroute we currently contemplate for an overall ures e 06 mg group a g pmethod of obtaining 7-acylamido-3-nucleophile-meththen be removed toform 3-methylthiomethyl-7-D-aa phenyl a aminoacetamido A3 cephem 4carboxylic grits-cephem-4-carboxyhc acid cephalosporm antibiacid as thezwitterion, hydrate, or salt with a pharmaceutically acceptable cationsuch as sodium or potas- The n e t on iS further exemplified by thefollowing sium, or anion such as the hydrochloride, nitrate, suldetailedexamples, which are not intended to limit the fate, phosphate, or thelike. These 3-methylthiomethylscope of starting materials or productsbut merely to A -cephalosporin compounds are effective asantibiotindicate the operation of the process and typical prepaics,administered either parenterally or orally. For this rations of newcompounds.

EXAMPLE 1 Preparation of t-butyl 7-(phenoxyacetamide)-3- bromomethyl-A-cephem-4-carboxylate To a stirred, cooled (l C.) solution of 0.440 g.('1 mmole) of 4-t-butyl 7-(phenoxyacetamido)-3-hydroxymethyl-A-cephem-4-carboxylate-l-oxide and 0.4 ml. of N,N-dimethylaniline in 15ml. of methylene chloride was added 0.2 ml. (2 mmoles) of phosphorustribromide in 10 ml. of methylene chloride dropwise over a.

10 minute period. The reaction was stirred an additional 20 minutes at*lO upon completing the addition. The reaction mixture was poured into aseparatory funnel and washed successively with 10 percent sodiumchloride in water, percent sodium bicarbonate in water, 3 percenthydrochloric acid solution, and water. The organic solution wasevaporated to dryness to give 0.33 g. of the tert-butyl 3-bromomethyl-7-phenoxyacetamido-M-cephem-4-carboxylate. A thin layer chromatogramshowed pure product and the structure was confirmed by nuclear magneticresonance (NMR) spectrum.

EXAMPLE 2 Preparation of t-butyl 7-(phenoxyacetamido)-3- chloromethyl-A-cephemA-carbocylatel-oxide.

A solution of 0.1 g. (0.25 mrnoles) of the tert-butyl3-hydroxymethyl-7-phenoxyacetamido-A -cephem-4- carboxylate-l-oxide and1 drop of pyridine in 10 ml. of anhydrous tetrahydrofuran was treatedwith 0.060 g. of

phosphorus pentachloride. The reaction mixture was stirred at 25 for 30minutes. The reaction mixture was then poured intoice water andextracted with methylene chloride. The methylene chloride solution waswashed with 5 percent sodium bicarbonate in water, dried over sodiumsulfate and evaporated to dryness. The mixture (0.106 g.) was separatedby preparative thin layer chromatography to give 0.035 g. of product. AnNMR spectrum verified .the st'ructure of the tertbutyl3-chloromethyl-7-phenoxyacetamido-A -cephem-4-carboxylatel -oxide.

EXAMPLE 3 Preparation of 7-phenoxyacetamido-3-acetoxymethyl-A -cephem-4-carboxylic acid.

A solution of 0.290 g. of t-butyl7-(phenoxyacetamido)-3-bromomethyl-M-cephemA-carboxylate in 10 ml. ofacetone was stirred for 24 hours with 0.250 g. of tetramethylammoniumacetate. A thin layer chromatogram revealed the presence of twocompounds. The solvent was evaporated to dryness and the residue waswashed with ethyl acetate. The ethyl ace tate solution was washed with 3percent hydrochloric acid and 5 percent sodium bicarbonate, dried oversodium sulfate, and evaporated to dryness to give 0.19 g. product. Theproduct was dissolved in 5 ml. offormic acid and stirred at 25 for 1hour. The acidic solution was poured into water and extracted with ethylacetate. The ethyl acetate solution was washed with 5 percent aqueoussodium bicarbonate and the basic solution was acidified. Extraction ofthe new acid solution with ethyl acetate and evaporation of the ethylacetate gave 0.072 g. of acidic material. A thin layer chromatogram anda 12 bioautograph of a paper chromatogram of the material showed it tobe 3-acetoxymethyl-7 phenoxyacetamido-A -cephem-4-carboxylic acid, aknown antibiotic. 7

EXAMPLE 4 p-Methoxybenzyl I 3-chloromethyl-7-phenoxyacetamido-A -cephemtcarboxylate To a solution of 150 mg. of p-methoxybenzyl 3-hydroxymethyl-7-phenoxyacetamido-A -cephem-4-.

carboxylate-l-oxide was added 12 drops of dry pyri:

dine and then l2 drops phosphorus trichloride. After stirring 2 hours atroom temperature, the reaction mixture was evaporated to dryness,diluted with ethyl acetate, and washed with cold 5 percent HCI,bicarbonate solution, 2 times with sodium chloride solution, dried overMgSO filtered and evaporated to give mg. of. i

an orange oil.

This oil was applied to two commercial preparative 7 thin layerchromatographic plates (2 mm.) and eluted 1 with a 1:1 benzeneethylacetate mixture. There was obtained 56 mg. of the p-methoxybenzyl3-chloromethyl- 7-phenoxyacetamido-A -cephem-4-carboxylate,. whichstructure was confirmed by nuclear magnetic resonance (NMR)spectroscopy.

The following additional exemplary compounds are prepared according tothe process of this invention by.

the procedures of the above examples.

1 l -Dimethyl-2-propenyl 3-chloromethyl-7-(p nitrophenylacetamido)-A-cephem-4-carboxylate 3-hydroxymethyl-7-(p-nitrophenylacetamido)-A+cephem-4-carboxylate-l-oxide.

Phthalimidomethyl 3-bromomethyl-7-phenylmercaptomethyl-A-cephem-4-carboxylate from. phosphorus EXAMPLE 5 tert-Butyl7-phenoxyacetamido-3-iodomethyl-A -cephem 4car-' boxylate A solution of0.380 g. of crude tert-butyl 7-phenoxyacetamido-3-bromomethyl-A-cephem-4-carboxylatel-oxide, prepared as described in Example 1, wasdissolved in 10 ml. of acetone and stirred at 25 C. for 1 hour with 0.5g. of potassium iodide. The resulting reaction mixture was centrifugedand the supernatantu? was evaporated in vacuo to give 0.40 g. of crudeproduct, tert-butyl 7-phenoxyacetamido-3-iodomethyl-Acephem-4-carboxylate. The NMR spectrum of i this product was similar to,but not superimposable on, the I spectrum of the 3-bromomethylderivative starting material which indicated the complete conversion tothe 3-iodomethyl derivative.

EXAMPLE 6 To a solution of Z-methyl-S-butynyl7-phenoxyacetamido-3-hydroxymethyl-A -cephem-4-carboxyacidic fromphosphorus trichloridei and l,l-dimethyl-2-propenyl 3-chloromethyl-7-( 3i late-l-oxide in 40 ml. ofmethylene chloride containing 0.4 ml. ofN,N-dim'ethylaniline, cooled at l C., there was added dropwise 0.4 ml.of phosphorus tribromide in 30 ml. of methylene chloride over a 45minute period. When the addition was completed, the reaction mixture wasstirred for an additional 30 minutes at l0 C. to insure completereaction. The solvent was removed under vacuum and the residue wasdissolved in an ethyl acetate/water mixture. The organic solution wasseparated from the aqueous phase and subse quently washed with percentsodium chloride aqueous solution, 3 percent hydrochloric acid solution,and then with a 5 percent sodium bicarbonate aqueous so lution. Thewashed organic solution was dried over sodium sulfate and evaporated todryness to give 0.78 g. of the 2-methyl-3-butynyl 7-phenoxyacetamido-3-bromomethyl-A -cephem-4-carboxylate as product. A thin layerchromatogram showed the presence of one component whose rf was differentfrom that of the starting material.

The following additional compounds are prepared by procedures describedabove:

p-Methoxybenzyl tolylacetarnido)-A -cephem-4-carboxylate-l-oxide fromphosphorus pentabromide and p-methoxybenzyl3-hydroxymethyl-7-(p-tolylacetamido)-A- cephem-4-carboxylatel -oxide;

p-Nitrobenzyl 3-brornomethyl-7-(4-trifluoromethylphenoxyacetamido )-A-cephem-4-carboxylate- 1 oxide from phosphorus oxybromide andp-nitrobenzyl 3-hydroxymethyl-7-(4'-trifluoromethyiphenoxyacetarnido )-A-cephem-4-carboxylatel oxide;

l,l-Dimethyl-2-pentynyl 3-chloromethyl-7-( 3 methoxyphenylacetamido)-A-cephem-4-carboxylate-l-oxide from phosphorus oxychloride and 1,1-dirnethyl-Z-pentynyl 3-hydroxymethyl-7-( 3 rnethoxyphenylacetamido)-A-cephem-4-carboxylate-Loxide;

Succinirnidomethyl 3-chloromethyl-7-(4'-cyanophenylacetamido)-A-cephem-4-carboxylate from phenylphosphonous dichloride andsuccinirnidomethyl 3-hydroxymethyl-7-(4'-cyanophenylacetamido)-A-cephem-4-carboxy1ate-l oxide; r

tcrt-Butyl 3-broinomethyl-7-[ (4'-aminomethyl phenylacetamido]-A-cephem-4-carboxylatel oxide from phosphorus oxybromide and tert-butyl3-hydroxyrnethyl-7-[4'-(aminomethyl)- phenylacetamido]-A-cephem-4-carboxylate-loxide;

2 ,2,2-trichloroethyl 3-chloromethyl-7-( 3 ,4-

dichiorophenoxyacetamido)-A-cephem-4-carboxylate from phosphorustrichloride and 2,2,2-trichloro3-hydroxymethyl-7-(3,4-dichlorophenoxyacetamido-A-cephem-4-carboxylate-1-oxide, and

Benzhydryl 3-bromomethyl-7-phenylacetamido-Acephem-4-carboxylate-l-oxide from phosphorus pentabromide and benzhydryl3-hydroxymethyl-7- phenylacetamido-N-cephem-4-carboxylate-l oxide.

Also, according to this invention we have found that the3-halornethyl-7-acylamido-3-cephem-4-carboxylate sulfoxide esters can bemade by reacting approximately equivalent amounts of the phosphorustribromide or or phosphorus trichloride with the3-hydroxymethyi-7-acylarnido-3-cephem-4-carboxylatel -oxide esters atrelatively low temperatures, below 25. By

3-bromomethyl-7-(pi compounds as indicated above. Such method isillustrated by the following example.

EXAMPLE 7 Preparation of tert-butyl7-(phenoxyacetamido)-3-bromomethyl-3-cephem-4- carboxylatel -oxide.

To a stirred solution of 0.208 g (0.5 millimole) of tert-butyl7-phenoxy-acetamido-3-hydroxymethyl-3- cephem-4-carboxylate-l-oxide in40 ml. of methylene chloride at 35C containing 0.060 g (0.50 millimole)of N,N-dimethyl-aniline, was added dropwise a solution of 10 ml. ofmethylene chloride containing 0.135 g (0.50 millimole) of phosphorustribromide. After the addition was completed the reaction mixture wasstirred at 35C for 1 hour. Then the solvents were evaporated in vacuoand the residue was suspended in ethyl acetate. The ethyl acetatesolution was washed three times with 50 ml. portions of 3 percenthydrochloric acid solution, once with saturated sodium bicarbonatesolution, once with water, and then dried over sodium sulfate andevaporated to dryness to give 0.160 g. of crude tert-butyl3-bromomethyl-7-phenoxyacetamido-3-cephem-4-carboxylate-l-oxide asproduct. The crude product mixture was separated on two 20 cm. by 0.2cm. silica gel preparative thin layer chromatography plates. Thecompound of intermediate polarity was isolated as 0.065 g of white foam.A nuclear magnetic resonance spectrum proved the identity of thecompound to be tert-butyl 3-bromomethyl-7-phenoxyacetamido-3-cephem-4-carboxylatel -oxide.

EXAMPLE 8 7 Acetamido 3 acetoxymethyl A cephem-4-carboxylic acid isprepared by reacting 7-aminocephalosporanic acid (7-ACA) with acetylchloride. The 7- acetamido-3 acetoxymethyl- A -cephem-4-carboxylic acidis treated with oxalyl chloride in the presence of a small amount ofN,N-dimethylformamide to form the corresponding acid chloride. This acidchloride of 7- acetamiclo-3-acetoxymethyl-A -cephem-4-carboxylic acid isdissolved in methylene chloride and the solution is treated withter't-butanol and triethylamine to form the tert-butyl7-acetamido-3-acetoxymethyl -A -cephem-4-carboxylate ester.

The tert-butyl 7-acetamido-B-acetoxymethyl-N- cephern-4-carboxylate isoxidized with a peracid such as meta-chloroperbenzoic acid inisopropanol/methylene chloride mixture to form the tert-butyl 7-acetamido-3-acetoxymethyl-A -cephein-4-carboxylatel-oxide.

The

tert-butyl 7-acetamido-3-acetoxymethyl-A cephern-4-carboxylate-l-oxideis treated with citrus acetylesterase by known procedures to obtain thetertbutyl 7-acetamido-3-hydroxymethyl-A -cephem-4-car- This product canbe used as an intermediate to prepare a wide variety of known and newcephalosporin antibiotics. For example, this product can be treated withmethanol to form the 3-methoxymethyl analog, or with methyl mercaptan toform the B-methylthiomethyl analog. Such compounds can then be reducedto the sulfide state, treated by the known PCl /CH OH/H O procedures tocleave the 7-acetyl group, re-acylated with any acryl group known tocontribute to good activity in the resulting A -cephalosporin acid. Forexample, the tert-butyl 7-amino-3-methylthiomethyl-Acephem-4-carboxylate ester nucleus compound can be acylated with analkyl mixed anhydride of an N-D-(tert-butoxycarbonylamido)phenylglycine,- and then thetert-butoxycarbonyl protecting group and the tertbutyl esters areremoved by known methods to form the 3methylthiomethyl-7-[D-2-amino-2-phenylacetamido]-A -cephem-4-carboxylic acid zwitterion (inner salt), aknown antibiotic.

EXAMPLE 9 The amino group of 7-aminocephalosporanic acid (7-ACA) isprotected with a formyl group by reacting 7-ACA with the mixed anhydrideformed by adding formic acid to acetic acid anhydride to form the7-formamido-3acetoxymethyl-N-cephem4-carboxylic acid. This N-protected7-ACA is esterified in the manner described in Example 8 to form thetert-butyl 7-formamido-B-acetoxymethyl M-cephem-4-carboxylate ester.This N-cephalosporin ester is oxidized as described in. Example 8 toform the tert-butyl 7-formamido-B-acetoxymethyl-A-cephem-4-carboxylate-1 oxide. This A -cephalosporin sulfoxide ester ishyrolyzed with citrus acetyl esterase to form the tert-butyl7-formamido-3hydroxymethyl-A -cephem-4carboxylate-l-oxide, which is thestarting material for the process of this invention.

Following the procedure of example 7, phosphorus tribromi'de is reactedwith tert-butyl 7-formamido-3- hydroxymethyl-A -cephem4carboxylate-loxide to form tert-butyl 7-formamido-3-bromomethyl-A-cephem-4-carboxylate of this invention.

This compound is useful as an intermediate in the production of knownand new cephalosporin antibiotics. For example, this compound can betreated with methanol to form the tert-butyl 7-formamido-3-methoxymethyl-A -cephem-4-carboxylatel oxide, the sulfoxide ester can bereduced with potassium iodide/acetyl chloride to form the tert-butyl7-formamido-3- bromomethyl-A -cephem-4-carboxylate, the formyl group canbe cleaved with mineral acid at l5 to 100C to form the7-amino-3methoxyrnethyl-N-cephem-4-carboxylate ester nucleus. Thisnucleus ester can be acylated with any acyl group known to contribute tothe formation of a cephalosporin compound having significant antibioticactivity. For example, the nucleus ester can be acylated with anactivated, N- protected form of D-phenylglycine to form the tertbutyl7-[D-2-(N-protected amino)-2'-phenylacetamido]-3methoxymethyl-A-cephem-4-carboxylate ester. The N-protecting group and the ester groupcan be removed by known procedures to form the 7- [D-2 amino-2'-phenylacetamido]-3-methoxymethyl- A -cephem-4-carboxylic acid, and aknown antibiotic.

16 We claim: 1. A compound having the formula wherein X is chlorine,bromine or iodineyR. is C; to C alkanoyl, C to C chloroalkanoyl, or anacyl group of the formula I I g where Ar is 2-thienyl or wherein m is aninteger of from Oto 4, n is an integer, of from I to 4, Z is oxygen orsulfur ora chemical bond, R' and R" are, separately, hydrogen or methyl,or when R' is hydrogen, R"" can be an N-protectedamino selected from thegroup consisting of N-tertbutoxycarbonyl)amino, amino,N-(allyloxycarbonyl)amino, N-(cyclopentyloxycarbonyl)-amino, and

c -alkyloxy, N-protected-alpha-aminoC to C -alkyl,

butoxycarbonyl, nitro, cyano, trifluoromethyl and w is f an integer offrom 1 to 2; and R is 2,2,2-trichloroethyl, C to C -tert-alkyl, C to C-tert-alkenyl, C 'toC -tertalkynyl, benzyl, methoxybenzyl, nitrobenzyl,phenacyl,

phthalimidomethyl, or succinimidomethyl. 2. A compound having theformula s R K cooR wherein R is phenoxyacetamido or phenylacetamido; Ris t-butyl or 2,2,2-trichloroethyl and X is selected.

N-(benzyloxycarbonyn- N-(2-methoxycarbonyl-lmethylvinyl)amino and n isl; and Y is hydrogen ora 7 substituent on the phenyl ring carbon atomssuch as flu- I orine, chlorine, bromine,'iodine, C to C -alkyl, C, to I5. A compound as defined in claim 1 wherein X is bromine, R isphenoxyacetyl, and R is C to C -tertalkyl.

6. A compound as defined in claim 5 wherein the compound is tert-butyl3-bromomethyl-7-phenoxyacetamido-3-cephem-4-carb0xylate-1-oxide.

UNITED STATES PATENT AND'TRADEMARK OFFICE CERTIFICATE OF CORRECTIONPATENT N0. 5,922,268 Page 1 of 3 DATED November 25, 1975 INVENTOR(S)Charles F. Murphy J. Alan Webber It IS certrfled that error appears mthe above-Mentrfred patent and that sard Letters Patent are herebycorrected as shown below:

Column 5, line 2, "Jan. 1971; should read --Jan. 25, 1971;".

Column 6, line 2, "are formed from the phosphorus pentahalide or phos-"should read --are formed from an approximately equimolar amount of atrivalent phosphorous trihalide when temperatures below about -25C. areused.

The fi-halomethyl-A -cephalosporin sulfoxide esters are formed from thephosphorus pentahalide or phos- UNITED STATES PATENT AND TRADEMARKOFFICE CERTIFICATE OF CORRECTION PATENT NO. 5,922,268 page Z f 3 DATEDNovember 25, 1975 INV ENTOR(S) Charles F. Murphy J. Alan Webber It IScert|f|ed that error appears In the above-ldentlfred patent and thatsard Letters Patent are hereby corrected as shown below:

Column 10, following line 16 the structures should read:

Column 15, line 66, "mide or' or phosphorus" should read -mide orphosphorus--.

UNITED STATES PATENT OFFICE Page 3 of 3 CERTIFICATE OF CORRECTION Pat3,922 8 Datea November 25 1975 Charles P. Murphy et a1.

Inventor(s) It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

Column 15, line 9, "acryl" should read acyl Signed and Scaled thistwenty-sixth D a) of .1111 y I 97 7 [SEAL] Arrest.

RUTH C. MASON C. MARSHALL DANN 8 ff Commissioner of Patents andTrademarks

1. A COMPOUND HAVING THE FORMULA
 2. A compound having the formula
 3. Acompound as defined in claim 1 wherein X is chlorine, R isphenoxyacetyl, and R1 is C4 to C6-tert-alkyl.
 4. A compound as definedin claim 1 wherein X is chlorine, R is phenoxyacetyl, and R1 ismethoxybenzyl.
 5. A compound as defined in claim 1 wherein X is bromine,R is phenoxyacetyl, and R1 is C4 to C6-tert-alkyl.
 6. A compound asdefined in claim 5 wherein the compound is tert-butyl3-bromomethyl-7-phenoxyacetamido-3-cephem-4-carboxylate-1-oxide.